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UNITED STATES PATENT Oriana.

GEORGE F. CUSHMAN, OF BARNET, VERMONT, ASSIGNOR TO HIMSELF, FRAN- CIS A. OUSHMAN, OF LEBANON, NEW HAMPSHIRE, AND ASA O. RUSSELL AND GEORGE S. OUSI-IING, OF LOWELL, MASSACHUSETTS.

PROCESS OF MAKlNG PAPER-PULP FROM WOODEN BLOCKS.

SPECIFICATION forming part of Letters Patent No. 329,370, dated October 27, 1885.

Application filed June 29, 1885. Serial No. 170,174.

To all whom it may concern Be it known that I, GEORGE I CUSHMAN, of Barnet, in the county of Caledonia and State of Vermont, have invented a new and useful Improvement in the Process of Making Paper- Pulp from Wooden Blocks, of which the following is a specification.

. The object of this invention is to facilitate the mechanical separation of wood fibers from IO the block direct, and to greatly, improve the quality of the pulp produced by'the succession of steps hereinafter described.

I have discovered that the production of wood pulp for papermaking, &c., commonly carried on by grinding the wooden blocks on a revolving stone, so as to disintegrate the fibers, may be greatly facilitated byapreliminary cooking of the block in a bath of boiling hot water with lime, soda-ash, or equivalent 2o chemical agent in solution, to soften the block, toughen the fibers, and lessen their lateral adhesion, and by subsequently grinding the blocks so treated to mechanically separate the loosened fibers. By my process the block is reduced to pulp with one-half the power required to grind a block not so treated, and the pulp produced is much softer, stronger, and more desirable, since the fibers are not broken up or comminuted, but are more nearly in their natural condition, with their lateral beards or filaments preserved, so that when reunited in the paper sheet special toughness and tenacity are attained.

In carrying out my inventiomlimmerse the 3 solid wooden blocks in a strong solution of lime, soda-ash, chloride of lime, or equivalent chemical agent, kept boiling hot by the introduction of steam or otherwise, and adapted to soften the blocks in readiness for grinding, and

0 I retain the blocks under treatment from ten to twenty-four hours, or until the liquid has had time to penetrate all parts of the block, and the lateral adhesion of the fibers is so weakened that they will readily separate by 5 the attrition of the grinding-stone without being broken short or reduced to a mere powder; and as the chemical action is most rapid in the direction of thelength of the fibers, I am accustomed to cut the block much shorter than is usual, or to form transverse saw-scarfs (Spccimcns.)

at intervals between its ends, in order that the solution may readily penetrate from each end to the center, so as to loosen and toughen the fibers throughout the block. The pressure of steam above the liquid in the tank tends to force the solution into all the pores of the immersed blocks. I then remove the blor K from the tank and subject them to the action of the grinders in the usual way, keeping a constant stream of water upon the stone; and l 6 find the disintegration to be effected with great rapidity, owing to the preliminary treatment received by the blocks, and also that no washing is required beyond what results from wetting down the stone. The pulp produced 6 5 is of superior quality, and as the blocks have absorbed only so much of the chemicals as is beneficial to the fiber, it is in condition for the successive steps in the production of various grades of paper of special strength, and for 7Q numerous other purposes in the arts. If preferrcd, however,this fiber may be mixed with hard stock made of other material, such mixture producing paper or board of exceptional toughness.

I am aware that many different methods of producing paper-pulp from vegetable fiber have been employed. One proposes splitting wood to suitable size and crushing it between rollers, so as to separate the fibers longitudi- 8o nally, afterward steeping such mechanicallycrushed fibers in a succession of baths, each warmer than the preceding one, with alternate rinsings, and, finally, boiling, bleaching, and grinding these separated fibers. Another proposes, preparatory to bleaching, to reduce the wood to small pieces, macerate them with cold water and lime for about a month, or a omit such maceration altogether,and grind on a stone turning in the trough containing the c liquid. A third party treats bamboo and like hollow vegetable products in a chemical solu tion until sufficiently softened to bale comp'actly for transportation, and subsequently disintegrates the material in the common 5 paper-maker s rag-engine. Another treats pieces of wood by first steaming them, then removing the acids generated in the steaming operation, next treating the steamed wood with alkali, and, finally, grinding or reducing the rec pieces to pulp. Steaming has been resorted to for the purpose of removing the bark from wooden blocks preparatory to grinding the solid parts thereof, and wood has also been 5 treated with water sprinkled on it from above, and steam simultaneously applied from beneath it, inorder to soften and cleanse it preparatory to grinding. All such processes I disclaim; but

[ Iclaim as my invention- 1. The herein-described process of treating wooden blocks for the production of pulp,

consisting in first cooking the blocks in a hot solution of lime, soda-ash, or equivalent chem- 1 ical substances, to promote lateral separation and toughening of the fibers, and afterward removing the blocks from such solution and subjecting them to the action of a grindingroller, substantially as and for the purpose set forth.

2. The herein-described process of producing paper-pul p from wooden blocks, consisting i.: sawing the blocks transversely to short lengths, chemically treating them in a hot liquid solution such as described, for the purpose of loosening and toughening the fibers, and subsequently disintegrating the fibers by grinding the blocks on a revolving stone, sub-. stantially as set forth.

In testimony whereof Ihave signed my name to this specifieation,in the presence of two subscribing witnesses, on this 12th day of June,

GEORGE J3. OUSHMAN.

Witnesses:

H. S. Roo'r,

NV. A. HorKINs. 

